Carbon, oxygen, hydrogen, and nitrogen - the four elements which are essential for life on earth - continuously cycle through different compartments of our Earth, the "spheres" that make up the Earth System: the biosphere (all living organisms), atmosphere (air & outer gas layers), hydrosphere (water) and geosphere/lithosphere (solid part). While cycling through the spheres, these elements are continuously subject to biological, chemical and physical changes.
Bound in varying organic compounds in living organisms, the essential elements are released from the biosphere and are transported and distributed throughout the atmosphere, geosphere and hydrosphere, where they may experience chemical or physical changes. From there, the elements may find their way back to the biosphere to be converted again by various organisms.
Since the cycles and transformations are interlinked and controlled by both the biology of the organisms as well as chemical and physical processes in the hydrosphere, geosphere and atmosphere, they are known as the "biogeochemical cycles of the elements". In research terms, the biogeochemical cycles are quantitative descriptions of the distribution of elements among components of the Earth System, including the processes that control the rates of transfer between spheres.
The trace gases carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and water vapor (H2O) are a main research focus of our institute and exemplify such interactions. Although the air contains only low concentrations of these gases, they have a decisive influence on the climate and, hence, on the conditions for life on Earth. The concentration and distribution of these gases is regulated by biological, chemical and physical processes that occur in the terrestrial biosphere, in the oceans and in the atmosphere, and is also affected by planetary and human influences. For example, changes in the Earth’s orbit around the sun and resulting fluctuations in insolation caused the Ice Age.
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